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Pinholes in new grp roof


I have a new GRP roof, 2 weeks old. Yesterday I noticed that there are lots of tiny pinholes over the roof surface. They appear to be in the top coat but I'm not sure how deep they might be. Is it normal for such pinholes to appear? if not how much of a problem might they be? And what are the options for a solution?

I had a response off 'Fibretech' to a related GRP question last week. Thanks and I would be interested in your thoughts as well as any one else with experience in GRP roofs.

Also who could I contact for an independent inspection of the roof.



5 Answers from MyBuilder Roofers

Best Answer

In the game we call that orange pell u need to strip old topcoat of whith a sander topcoat as a wax in it so u carnt coat over it make sure u acetone the hole roof before u apply new top coat


Answered 16th Apr 2016

Hi, it sounds like the installer has used insufficient resin on the mat or the mat has been poorly consolidated. Pin holes could also be cause if the topcoat is too thick, but it normally cracks when this occurs.

Pinholes can lead to moisture getting into the deck and premature failure.

Ideally the roof should at a bare minimum be sanded down with P120 and a new top coat applied.

Hope this helps...


Answered 5th Jun 2014

It's quite common and I see this time and time again. It's not wrongly installed and will not leak, however would suggest that the top coat has not been applied thick enough. Key sanding and then applying more top coat would sort this out, but it's not an issue for you to be concerned.


Answered 5th Jan 2017

Use a epdm rubber roof. And save yourself alot of hasstle. I trained at topseal. Never use it again.
Anything that sets hard can crack..... full stop. Topseal is over rated and a costly waste of time. It needs topcoating every year! If your lucky to get to 10 years without it cracking!


Answered 28th Jun 2017

what I can gather from your information, the base coat must be covered to a smooth finish with no pin holes because the top coat will form to what is on the bottom coat, if you don't get a smooth finish on the bottom, chances are you won't on the top coat. suggestion: if you are thinking of re coating the top coat, make sure you sand it down to key in new covering. hope it helps.


Answered 4th Jun 2014

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